An important part of Michelangelo’s plan for the fortification of Florence was to erect bastions covering the hill of S. Miniato.  Any one who stands upon the ruined tower of the church there will see at a glance that S. Miniato is the key to the position for a beleaguering force; and “if the enemy once obtained possession of the hill, he would become immediately master of the town.”  It must, I think, have been at this spot that Buonarroti was working before he received the appointment of controller-general of the works.  Yet he found some difficulty in persuading the rulers of the state that his plan was the right one.  Busini, using information supplied by Michelangelo himself at Rome in 1549, speaks as follows:  “Whatever the reason may have been, Niccolo Capponi, while he was Gonfalonier, would not allow the hill of S. Miniato to be fortified, and Michelangelo, who is a man of absolute veracity, tells me that he had great trouble in convincing the other members of the Government, but that he could never convince Niccolo.  However, he began the work, in the way you know, with those fascines of tow.  But Niccolo made him abandon it, and sent him to another post; and when he was elected to the Nine, they despatched him twice or thrice outside the city.  Each time, on his return, he found the hill neglected, whereupon he complained, feeling this a blot upon his reputation and an insult to his magistracy.  Eventually, the works went on, until, when the besieging army arrived, they were tenable.”

Michelangelo had hitherto acquired no practical acquaintance with the art of fortification.  That the system of defence by bastions was an Italian invention (although Albert Duerer first reduced it to written theory in his book of 1527, suggesting improvements which led up to Vauban’s method) is a fact acknowledged by military historians.  But it does not appear that Michelangelo did more than carry out defensive operations in the manner familiar to his predecessors.  Indeed, we shall see that some critics found reason to blame him for want of science in the construction of his outworks.  When, therefore, a difference arose between the controller-general of defences and the Gonfalonier upon this question of strengthening S. Miniato, it was natural that the War Office should have thought it prudent to send their chief officer to the greatest authority upon fortification then alive in Italy.  This was the Duke of Ferrara.  Busini must serve as our text in the first instance upon this point.  “Michelangelo says that, when neither Niccolo Capponi nor Baldassare Carducci would agree to the outworks at S. Miniato, he convinced all the leading men except Niccolo of their necessity, showing that Florence could not hold out a single day without them.  Accordingly he began to throw up bastions with fascines of tow; but the result was far from perfect, as he himself confessed.  Upon this, the Ten resolved to send him to Ferrara to inspect that renowned work of defence.  Thither accordingly he went; nevertheless, he believes that Niccolo did this in order to get him out of the way, and to prevent the construction of the bastion.  In proof thereof he adduces the fact that, upon his return, he found the whole work interrupted.”